Back fire.
(a)
A fire started ahead
of a forest or prairie fire to burn only against the wind, so that
when the two fires meet both must go out for lack of fuel.
(b)
A premature explosion in the cylinder of a
gas or oil engine during the exhaust or the compression stroke,
tending to drive the piston in a direction reverse to that in which it
should travel; also, an explosion in the exhaust passages of such ah
engine.
© Webster 1913.